For english-only speaking:
This book is in german. English title would be: Reality of flying saucers. The book is basically a lifestory of one of earliest and most original inventors of flying saucers, german constructor Andreas Epp. Epp being an intuitive genius proposed the saucer design before WW2 and some were even made and tested with various construction teams right before the end of WW2. These saucers used conventional propulsion technology: rotors and rocket engines. Epp was one of those forgotten geniuses like Tesla and others, being chased after the war and ridiculed, he died poor in 1997. Many pictures, plans and other technical data, 170 pages. Worth a look even if you don't speak a word german.
Die Lebensgeschichte von Andreas Epp, eine deutsche Flugscheibenlegende und Genie. Er erfand die deutschen Flugscheiben mit konventionellen Treibwerken. Viele Abbildungen und Plane, 170 Seiten. Jeder sollte dieses Buch lesen.